/*  General C++ Object Thunking class

    - allows direct callbacks to non-static C++ class functions
    - keeps track for the corresponding class instance
    - supports an optional context parameter for the called function
    - ideally suited for class object receiving interrupts (NVIC_SetVector)

    Copyright (c) 2014-2015 ARM Limited

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/
#ifndef __CTHUNK_H__
#define __CTHUNK_H__

#define CTHUNK_ADDRESS 1

#if defined(__CORTEX_M3) || defined(__CORTEX_M4) || defined(__thumb2__)
#define CTHUNK_VARIABLES volatile uint32_t code[1]
/**
    CTHUNK disassembly for Cortex-M3/M4 (thumb2):
* * ldm.w pc,{r0,r1,r2,pc}

    This instruction loads the arguments for the static thunking function to r0-r2, and
    branches to that function by loading its address into PC.

    This is safe for both regular calling and interrupt calling, since it only touches scratch registers
    which should be saved by the caller, and are automatically saved as part of the IRQ context switch.
*/
#define CTHUNK_ASSIGMENT m_thunk.code[0] = 0x8007E89F

#elif defined(__CORTEX_M0PLUS) || defined(__CORTEX_M0)
/*
    CTHUNK disassembly for Cortex M0 (thumb):
* * push {r0,r1,r2,r3,r4,lr} save touched registers and return address
* * movs r4,#4 set up address to load arguments from (immediately following this code block) (1)
* * add r4,pc set up address to load arguments from (immediately following this code block) (2)
* * ldm r4!,{r0,r1,r2,r3} load arguments for static thunk function
* * blx r3 call static thunk function
* * pop {r0,r1,r2,r3,r4,pc} restore scratch registers and return from function
*/
#define CTHUNK_VARIABLES volatile uint32_t code[3]
#define CTHUNK_ASSIGMENT do {                              \
        m_thunk.code[0] = 0x2404B51F; \
        m_thunk.code[1] = 0xCC0F447C; \
        m_thunk.code[2] = 0xBD1F4798; \
    } while (0)

#else
#error "Target is not currently suported."
#endif

/* IRQ/Exception compatible thunk entry function */
typedef void (*CThunkEntry)(void);

template<class T>
class CThunk {
  public:
    typedef void (T::*CCallbackSimple)(void);
    typedef void (T::*CCallback)(void* context);

    inline CThunk(T* instance) {
        init(instance, NULL, NULL);
    }

    inline CThunk(T* instance, CCallback callback) {
        init(instance, callback, NULL);
    }

    ~CThunk() {

    }

    inline CThunk(T* instance, CCallbackSimple callback) {
        init(instance, (CCallback)callback, NULL);
    }

    inline CThunk(T& instance, CCallback callback) {
        init(instance, callback, NULL);
    }

    inline CThunk(T& instance, CCallbackSimple callback) {
        init(instance, (CCallback)callback, NULL);
    }

    inline CThunk(T& instance, CCallback callback, void* context) {
        init(instance, callback, context);
    }

    inline void callback(CCallback callback) {
        m_callback = callback;
    }

    inline void callback(CCallbackSimple callback) {
        m_callback = (CCallback)callback;
    }

    inline void context(void* context) {
        m_thunk.context = (uint32_t)context;
    }

    inline void context(uint32_t context) {
        m_thunk.context = context;
    }

    inline uint32_t entry(void) {
        return (((uint32_t)&m_thunk) | CTHUNK_ADDRESS);
    }

    /* get thunk entry point for connecting rhunk to an IRQ table */
    inline operator CThunkEntry(void) {
        return (CThunkEntry)entry();
    }

    /* get thunk entry point for connecting rhunk to an IRQ table */
    inline operator uint32_t(void) {
        return entry();
    }

    /* simple test function */
    inline void call(void) {
        (((CThunkEntry)(entry()))());
    }

  private:
    T* m_instance;
    volatile CCallback m_callback;

    // TODO: this needs proper fix, to refactor toolchain header file and all its use
    // PACKED there is not defined properly for IAR
    #if defined (__ICCARM__)
    typedef __packed struct {
        CTHUNK_VARIABLES;
        volatile uint32_t instance;
        volatile uint32_t context;
        volatile uint32_t callback;
        volatile uint32_t trampoline;
    }  CThunkTrampoline;
    #else
    typedef struct {
        CTHUNK_VARIABLES;
        volatile uint32_t instance;
        volatile uint32_t context;
        volatile uint32_t callback;
        volatile uint32_t trampoline;
    } __attribute__((__packed__)) CThunkTrampoline;
    #endif

    static void trampoline(T* instance, void* context, CCallback* callback) {
        if (instance && *callback) {
            (static_cast<T*>(instance)->**callback)(context);
        }
    }

    volatile CThunkTrampoline m_thunk;

    inline void init(T* instance, CCallback callback, void* context) {
        /*  remember callback - need to add this level of redirection
            as pointer size for member functions differs between platforms */
        m_callback = callback;

        /* populate thunking trampoline */
        CTHUNK_ASSIGMENT;
        m_thunk.context = (uint32_t)context;
        m_thunk.instance = (uint32_t)instance;
        m_thunk.callback = (uint32_t)&m_callback;
        m_thunk.trampoline = (uint32_t)&trampoline;

        __ISB();
        __DSB();
    }
};

#endif/*__CTHUNK_H__*/
